This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We have obtained crystals of myosin motor (myosin VI and Dictyostellium myosin II) that can potentially provide important structural information to help trap intermediates in their ATPase cycle and understand how a myosin can work under load. In collaboration with Dr. Sol M. Gruner and Dr. Chae Un Kim at Cornell, we would like to collect data using their newly developed high-pressure cryo-cryocooling approach. Myosin crystals can diffract beyond 2.0 [unreadable] resolution under normal cryogenic conditions. First tests performed on ID27 (ESRF France) show that they resist pressure quite well. We hope that using high-pressure under cryocooling condition will give new insights to understand how myosin functions. We are therefore requesting two days of beam time at CHESS to test the effects of high-pressure cryocooling on the diffraction of these crystals, and if successful, to collect full native datasets.